Measuring the health of Mt. Tam

Maintaining a healthy, vibrant and diverse Mt. Tam begins with understanding how key ecological resources are faring, and how we can better care for this iconic and beloved place.

One Tam partners and Bay Area scientists have come together to try to answer the question: How healthy are Mt. Tam's natural resources?

North American River Otter

Photo by Mark Van Bergh

Coast Redwood Communities

Photo by Jessica Weinberg/NPS

Threespine Stickleback

Photo by Jessica Weinberg

Coho Salmon in Lagunitas Creek

Photo by Casey del Real/NPS

Steelhead Trout

NPS Photo

Serpentine Barren Endemics

Photo by Rachel Kesel/One Tam

Nothern Spotted Owl

NPS Photo

Invasive Species

Photo by Jean Pawek

Grassland Communities

Photo by Mason Cummings/Parks Conservancy

Maritime Chaparral

Photo by Andrea Williams/MMWD

American Badger

Photo by Yathin

Riparian Birds

Photo by Mick Thompson

Coast Redwood Forests

Photo by Jessica Weinberg

Plant Disease

USFS Photo

Shrublands

NPS photo

Open-canopy Oak Woodlands

MMWD Photo

Coho Salmon in Redwood Creek

Photo by Jessica Weinberg

Grasslands

Photo by William Follette

Conifer Forest-Mixed Hardwood Forest Birds

Photo by Alan Schmierer

Climate-vulnerable Birds

Photo by Charles Wohlers

Foothill Yellow-legged Frog

Photo by Ian Austin

Sargent Cypress

Photo by William Follette

Grassland Birds

Photo by Ken Schneider

Climate Change

Photo by Ken-ichi Ueda.

Open-canopy Oak Woodland Communities

MMWD Photo

Shrubland Communities

Photo by Brian Washburn

Osprey

Photo by Michael Utin

Native Mammal Diversity

Marin Wildlife Picture Index Project Photo

Shrubland Birds

Photo by Ken Schneider

California Red-legged Frog

Photo by Will Elder/NPS

Oak Woodland Birds

Photo by Nagarajan Kanna

Fire

Photo by Ken-ichi Ueda

Western Pond Turtle

Photo by Sami Kreling

Biodiversity

Overall biodiversity on Mt. Tam is in Fair condition. Some taxonomic groups have experienced local or global extirpations and include species that are in perilous condition, while others are faring better with limited extinctions and generally healthy populations of extant species. The trends in overall biodiversity are relatively Unchanged, though some taxonomic groups are faring better than others.

The health of the overall biodiversity of Mt. Tam is represented by a collection of key taxonomic groups seen in the figure below. Each group has one equal segment, and each segment was given its own condition, trend, and confidence score by aggregating the metrics of the species within them.

Plants

Biodiversity for plants has a cautionary condition and a downward trend. There are over 700 native species, but also over 300 non-native species. While some non-native species have limited distribution and impact, many others are noxious invasives that are impacting native species and processes. In addition, there have been 68 documented likely plant extirpations and of the known extant native plant species, 43 are considered rare, threatened, or endangered.

Birds

For birds, the aggregated condition and trend was calculated from the species trait-status database, which includes species that were chosen as good representatives of the whole bird population on Mt. Tam. The individual status and trends of the indicator species were rolled up to habitat community level, then aggregated again to obtain an overall condition and trend.

Mammals, Fish, Amphibians, & Reptiles

The other taxonomic groups were assessed by aggregating the condition and trends of the individual indicators within that group. For example, the mammal grouping included native mammal diversity, American badgers (Taxidea taxus), and North American river otters (Lontra canadensis). Based on this level of analysis, birds and mammals are in Good condition. Amphibians and reptiles are in Fair condtion, mainly because of the precarious state of the mountain's foothill yellow-legged frog (Rana boylii) populations. Fish are in poor condition as a result of declines in coho salmon (Oncorhynchus kisutch) numbers in Redwood and Lagunitas creeks.